The invention relates to a tool for deep-drawing and sealing open plastic shells,whereby the tool has a substantially flat edge which at least partly encompasses the open side of the shell-shaped metal body of the tool in one plane.
It is known to make packs for liquids from deep-drawable plastic material whereby panel-shaped blanks are heated in a flat or planar condition on hot plates and when a sufficiently high temperature has been reached they are conveyed to a shell-shaped deep-drawing tool. Disposed at the open side of the tool is an edge which substantially completely encompasses the sunken region of the tool, and this edge engages the frame-like outer edge of the flat plastic panel by clamping it in such a way that the region inside the frame can be deep-drawn by deformation. This gives rise to a deep-drawn plastic shell which is open on one side and which is outwardly embraced by a seam disposed in one plane. A plastic half shell of this kind can be joined to a plastic shell oppositely disposed thereto.
It is true that during deep-drawing the plastic material is at a temperature required to seal the outer seam of the first plastic shell to that of the second plastic shell. However, as known, the deep-drawing tool is cooled so that the deep-drawn plastic bodies cool and solidify. To join two deep-drawn plastic shells together, it was therefore necessary to heat the plastic material further, at least in the region of the outer seam, in order to reach the required high sealing temperature. This additional heating process not only uses up energy but also time, thereby reducing the output and efficiency of the pack machines.
To overcome these problems, the aim of the invention is to improve the tool of the kind mentioned above so that the outer seam of a plastic shell, deep-drawn by the metal body of the tool, can be joined by sealing without the additional supply of heat.